A multidrug-resistant strain of E. coli, potentially even more dangerous than the superbug MRSA, has been discovered living in Antarctic seawater.

Escherichia coli bacteria, better-known as E. coli, are common in the lower intestines of humans. That means they go everywhere people go - even Antarctica.

Many strains of E. coli are harmless when ingested, but some are deadly - as seen during last year's major outbreak of foodborne E. coli in Europe, as well as smaller U.S. outbreaks in Ohio, Oregon, Tennessee and Virginia. And while antibiotics are rarely used to treat food poisoning, it's nonetheless troubling that many E. coli strains can now withstand such medicine when it is needed - a phenomenon known as antibiotic resistance.

Drug-busting microbes are mainly a problem in hospitals, whether it's MRSA, C. difficile or NDM-1 superbugs. But they're increasingly common in the broader environment, too, as illustrated by a recent study in the journal Applied and Environmental Microbiology.

In that study, a team of scientists found E. coli thriving in seawater samples taken off the coast of Antarctica. But in a quarter of those samples, they also found E. coli with a specific gene that produces an enzyme called ESBL, which can destroy penicillin, cephalosporins and other related antibiotics. "This is the first record of ESBL-producing enterobacteria from Antarctica," the researchers point out in their abstract.

The rise of drug-resistant bacteria is widely blamed on overuse of antibiotic drugs, a practice that gives fast-evolving microbes more chances to mutate their way out of trouble. So how did these cutting-edge E. coli wind up in Antarctica? The scientists have a theory about where they might have come from: other scientists.

For starters, the ESBL-producing bacteria have "genotypes and sequence types indicative of a human-associated origin." Plus, the samples were collected between 10 and 300 meters from Chile's Antarctic research stations, with concentrations of superbugs higher in samples taken closer to sewage outflows. The facilities have "virtually no sewage treatment in place," New Scientistreports, although some Antarctic stations have reportedly begun shipping out human waste for incineration after the discovery of gut bacteria nearby.

This could mean superbugs are surviving in the wild, especially since previous research has shown E. coli can retain drug-resisting genes even after their drug exposure has ended. They would still need animal hosts in the wild, though, and penguins near the Chilean research stations reportedly show no signs of ESBL. Björn Olsen, the study's lead author, tells New Scientist he's now checking local seagulls, since he has found similar microbes among gulls in France. (A 2007 study also found non-ESBL E. coli infecting Antarctic fur seal pups.)

While it seems unlikely any people will be sickened by E. coli in the Southern Ocean, the overall spread of ESBL-producing superbugs is a concern, the researchers note, and could ultimately prove even more dangerous than MRSA. That's because the ESBL gene is in a section of DNA that can be acquired by many different bacterial species, similar to the recently discovered class of NDM-1 superbugs in India.

"If these genes are in Antarctica," Olsen tells New Scientist, "it's an indication of how far this [problem] has gone."